I think if you want to get a PR above 3, you should build backlinks using your keywords at the VERY Beginning of your sites from higher PR sources.
I knew it had to be with the Web 2.0 sites. I have used the same techniques to get my Squidoo lenses and Hub pages onto the first page of Google. That is how I make my affiliate money.
how much links are considered to much per time? Can i build 1000 backlinks per month? What about 5000? What is considered normal amount of backlinks per month?